Pressure balanced double porting servo valve



y 1, 1963 J. w. BROOME 3,090,400

PRESSURE BALANCED DOUBLE PORTING SERVO VALVE Filed May 16, 1960 5Sheets-Sheet 2 INVENTOR JOSEPH W BROOME ATTORNEY y 1, 1963 J. w. BROOME3,090,400

PRESSURE BALANCED DOUBLE PORTING SERVO VALVE Filed May 16, 1960 3SheetsSheet 3 FIG. 9

us may H4 H6 z v zgs v 1 FIG. IO IO 3H2 IO INVENTOR 133' JOSEPH 144BROOME F 7W0?! M IG. ll ATTORNEY United gtates Patent 3,099,400 PRESSUREBALANCED DQUBLE PQRTHNG SERVO VALVE Joseph W. Browne, South Sudhury,Mass, assignor to The Gilgear Company, Milwaukee, Wis. Filed May 16,1960, Ser. No. 29,238 2 Claims. (Cl. 137-622) This invention relates toan improved valve construction for a valve of the flat faced type andmore particularly to a pressure balanced flat faced servo valve.

The present valve is of the four way type illustrated in applicants US.Patent 2,939,483. The improvement herein consists of providing pressurebalance for a moveable valve plate together with means for doubling theflow capacity of the valve. The construction is such that the inertia ofthe moving element of the valve is not materially increased over thatfor a moving element having (flow only along one face and providingone-half of the present flow capacity. The present valve is capable ofcontrolling large hydraulic power in response to a minimum input signaland is capable of fast response to the input signal, as described in U.8. Patent 2,939,483.

It is an object of this invention to provide an improved valve having aminimum of friction between moving and stationary parts. Another objectof the invention is to provide a valve of the fiat faced type having amoveable valve element that .is balanced by operating pressure appliedto both faces of the valve. Another object of the invention is toprovide a fiat faced valve having a moveable valve element that issymmetrically constructed on opposite valve faces along which .acontrolled parallel flow of the pressure fluid is provided. Anotherobject of the invention is to provide an improved method of making andassembling the valve so that the surfaces defining the criticaldimensions of the valve are more easily and accurately obtained.

Other objects and advantages may be apparent upon a reading of thefollowing description taken with the accompanying drawings, in which:

FIG. 1 is a view in elevation of a servo valve embodying the presentinvention and shows the valve connected to an operating motor and showsflow passages of the valve schematically connected in a servo controlledbydraulic system; the valve proper is shown in cross section taken alongthe line 1-1 of FIG. 4;

FIG. 2 is a view of the valve head of FIG. 1 taken along the line 2-2thereof;

FIG. 3 is a view taken along the line 3-3 of FIG. 1 and shows themoveable valve member on the valve block;

FIG. 4 is a view taken along the line 4-4 of FIG. 1 looking down on theface of the valve block;

FIG. 5 is a view taken along line 5-5 of FIG. 3;

FIG. 6 is another valve similar to that shown in FIG. 1, and is a viewin cross sectional elevation taken along line 6-6 of FIG. 7;

FIG. 7 is a view taken along the line 7-7 of FIG. 6 to better show thesections of the valve;

FIG. 8 is a view in elevation taken along the line 8-8 of FIG. 9 ofanother valve embodying the present invention and includes returnpassages in the valve block;

FIG. 9 is a view taken along the line 9-9 of FIG. 8 to show the sectionsof the valve;

FIG. 10 is a view in elevation taken along the line 10-10 of FIG. 11showing another valve embodying the present invention and in which thepressure supply passage is normally closed by :a land on the valveplate; and

FIG. 11 is a view taken along the line 11-11 of FIG. 10 to better showthe sections of the valve.

Referring to the drawing and particularly to 'FIG. 1, a four way fiatfaced valve 1 embodying the present invention and as shown generally inFIG. 1 comprises a valve block *2, a valve head 3 rigidly secured by'bolts 4 to the valve block and spaced therefrom by spacer blocks 6,FIG. 5 through which the bolts extend, :and a valve plate 7 disposedbetween the valve head and valve block and adapted for rectilinearmovement therebetween.

The valve plate 7 is supported by a pair of leaf type springs 8 whichare longitudinally rigid and laterally resilient and hold the valveplate 7 in spaced relation between the valve head 3 and valve block 2and normally hold the valve plate in a center 'or null position in whichposition the valve is essentially closed. The' springs *8 have theirupper ends integrally joined to opposite ends of the valve plate 7 andtheir lower ends integrally joined to mounting feet 9 that are bolted toa base 11 for the valve block 2.

The valve block 2 is provided with a supply passage 12 located centrallyof the valve block between a pair of control passages 13, 14 which attheir openings in the valve face of the valve block define controlchambers 1'5, 16. The face of the valve head has recesses formed thereindelining control chambers 17, 1'8 aligned respectively with the controlchambers 15, 16 in the valve block.

The valve plate 7 has opposite faces symmetrically constructed whichinclude a pair of spaced lands 21, 22 which normally align with thecontrol chambers 15 to 18 in the valve head and valve block. The edgesof the lands and of the control chambers cooperate to provide flowcontrol orifices which govern the rate of flow of fluid to and from thecontrol chambers along the faces of the valve members.

The lands 21, 22 of the valve plate define pressure chambers 19, 20therebetween, and these pressure chambers '19, 2!) on opposite sides ofthe valve plate are interconnected by one or more transverse passages orholes 23 through the section of the valve plate between the lands. 7

The land portions of the valve plate also have transverse passages orholes 24 therethrough which interconnect aligned control chambers 15 and17 and aligned control chambers 16 and 118 in the valve head and valveblock. Thus, the pressure of fluid in the pressure chambers 19 is alwaysequal on opposite sides of the valve plate, and the pressures of fluidin the control chambers 15 to 18 are always equal on opposite faces ofthe lands, whereby the valve plate is always pressure balanced.

The supply passages 12 and the control passages 13, 14 in the valveblock have openings in the bottom of the block which are adapted forconnection in an eX- ternal hydraulic circuit. The valve block may beprovided with fluid return passages which connect to return chambers 33,34, or as indicated in FIG. 1, such return is provided by way of areservoir 25 formed by a housing, not shown, into which fluid from thereturn chambers 33, 34 is discharged.

The valve is shown schematically connected to regulate the tlow of fluidfrom a pump 26 in either direction to a hydraulic motor 27. The pump 26has an output that is connected to the supply passage 12 of the valve 3block 2 and the pump suction is connected to a reservoir 25. The loadhydraulic motor '27 is connected hydraulically across the controlpassages 13, 14.

A servomotor for controlling movement and displacement of the valveplate 7 from its null position if provided by a torque motor 28 having amoveable member 29 which transmits its motion through a rod 3! to movethe valve plate 7 rectilinearly between the valve head 3 and valve block2. Thus, the displacement and direction of displacement of the valveplate 7 is controlled in accordance with the command of the torque motor'28.

In FIG. 1, the torque motor 28 holds the valve plate 7 displacedslightly to the right of its null position whereby flow of fluid is tothe right from the pressure chambers 19 along opposite faces of thevalve plate to the right control chambers 16, 18 and then through theright control passage 14 to the right end of the hydraulic motor 27.Fluid is discharged at the left end of the hydraulic motor 27 and flowsinto the left control passage 13 and then into left control chambers 15,17. 'From the left control chambers the fluid flows to the left along'opposite faces of the left lands 2 1 into return or discharge chamber33 along the outer section of the valve plate from which fluid may spillout over the valve for collection in the reservoir 25 and return to thepump 26.

If the valve plate 7 were displaced to the left of its null position,the iluid would flow from the pressure chambers 19, 20 to the leftcontrol chamber 15, 17 and to the left end of the hydraulic motor .27.Fluid discharged from the right end of the hydraulic motor would enterright control chambers 16, 18 and discharge into chamber 34 for returnto the pump.

The return or discharge area of the valve plate at opposite ends thereofis closed in the direction of movement of the valve plate by bafileplates 31, 32 secured to the outer sides of the valve head and valveblock. These baflle plates extend the width of the valve'plate and thuscause fluid discharging from the valve to spill out transversely of thedirection of valve plate movement. The bafile plates 31, 32 beingsecured to the stationary valve head 2 and valve block 3 partiallyenclose return chambers 33, 34 outwardly of the lands so that the fluidreacts on the adjacent land 21'or '22 and produces an effective forcetending to hold the valve open.

Thus the valve controls the flow of fluid therethrough and providespressure balance for the valve plate and flow along opposite faces ofthe valve plate to double the flow capacity of the valve for each valvedisplacement.

Valve block 2 as can readily be seen from FIGS. 1

'and 4 is made up of three sections which include a central section 37confined between two outer sections 36 and 38. The central section 37 isa single block having a Width equal to the spacing between the outervertical surfaces of the lands 2 1, 22 so that outer vertical surfaces39, 40 of the central section are normally in the plane of the outervertical surfaces of the lands. Outer section 36 has a vertical surface41 which abuts vertical surface '39 of the central section and its edgecooperates, with the outer edge of land 21 to meter flow from controlchamber 15 to return chamber 33. Outer section 38 has a vertical surface42 which abuts vertical surface 49 of the central section and its edgecooperates with the outer edge of land 22 to meter flow from controlchamber 16 to return chamber 34.

Supply passage 12 in the central section 37 is provided by a pair ofvertically drilled holes, and control passages '13, Marc provided byvertical slots formed in the outer vertical surfaces 39, '40 of thecenter section which abuts the surfaces 41, 42 of the outer sections 36,38. The depth of the slots forming the control passages 13 and 14 aresuch that their vertical bottom surfaces 43, 44 are spaced apart equalto the spacing between the adjacent or inner vertical surfaces of thelands 21, 2 at least at the upper control chamber defining portions ofthe control passages. The slots defining the control chambers aretherefore made to a depth equal to the width of each land 21, 22. Thecentral section thus formed includes the four critical surfaces whichmust lie in the planes of the four parallel vertical surfaces of thelands, when the valve plate is at null position. Forming the controlchambers by providing slots in the outer vertical surfaces of thecentral section thus provides using a single lamina to make the centralsection with the four critical surfaces which must be accurately facedand spaced relative to one another.

The sections 36, 37 and 38 are secured together by bolts 46 which extendhorizontally through the sections to clamp them together and welds 47 atthe juncture of vertical end surfaces of the central section and outersections secure the sections so their valve faces remain coplanar.

The valve head 3 is constructed to present a valve face with controlchambers therein having vertical surfaces in alignment with the criticalvertical surfaces of the valve block so that their metering edges arecorrespondingly accurately spaced. T 0 best accomplish this arrangement,the valve head 3 is formed, FIGS. 1 and 2, of a single block and slotsare machined across its valve face to present vertical surfaces 39a, 43ain the slot defining control chamber .17 and vertical surfaces 40a, 44ain the other slot defining control chamber 18; these vertical surfacesalign With corers'pondingly numbered vertical surfaces (without thesubscripts) of the central section of the valve block. Opposite ends ofthese slots in the valve head are closed by insert plates 48 fittedtherein and suitably secured by pins 49 which may be welded to the blockand insert plates.

The valve plate 7 has opposite faces symmetrically formed and may bemade from a piece of stock with the pressure chambers 19 and 20- formedbetween the lands by a slot machined across the plate. The adjacentvertical surfaces of the lands which have metering edges may readily bemachined and accurately faced. The slot between the lands is closed atopposite ends by U-shaped members 51 whose legs 52 form the closingwalls for the slots. The U-shaped members are secured to the valve plateby rivets 50, FIG. 3.

The valve 1a shown in FIG. 6 differs from that shown in FIG. 1 in thatthe valve head 3a and valve block 2a each comprise five sections orlaminations. The metering edges of the control chambers in the valvehead and valve block are provided by vertical surfaces of difierentsections, wherein the number of sections is one more than the number ofmetering edges. Valve block 2a comprises sections 61 through 65. Centersection 63 contains vertical holes providing supply passage 12. Thewidth of the center section is equal to the spacing between the adjacentmetering edges of the lands 21, 22. so that the vertical surfaces of thecenter section provide the metering edges of the valve block whichcooperate with the adjacent edges of the lands.

Outer sections 61 and 65 of the valve block are spaced from the centersection 63, as seen in FIG. 7, by spacer sections 62, 62' and 64, 64,respectively. One spacer section is made up of spacers 62 and 62 whichare spaced front and back from each other to provide control passage-l3therebetween whose upper end defines a control chamber '15. The otherspacer section is made of spacers 64, '64 which are spaced front andback from each other to provide control passage 14 therebetween whoseupper end defines a control chamber '16. The spacer sections are made toa Width equal to the width of each of the lands 21, 22. The sections areclamped rigidly together by bolts 46 and are further secured to maintaintheir valve faces coplanar by welds along the vertical joints at theends of the sections.

The valve head3a comprises sections 71 through 75 clamped rigidlytogether by a through bolt 76 and further secured to maintain theirvalve faces coplanar by suitable welds 47 along the joints of adjacentsections. Each of these sections 71 to 75 corerspond in width to thesections 61 to 65 of the valve block. Center section 73 is made equal tothe spacing between control chambers 17 and 18 and the spacing betweenadjacent vertical surfaces of the lands 21, 22, so that their adjacentmetering edges cooperate to provide flow control orifices. Outersections 71 and 7-5 are spaced from the center section 73 by spacersections 72 and 74 each being slotted to provide the control chambers17, 18.

FIGS. 8 and 9 show a four way valve that is pressure balanced andprovides for parallel fluid flow along both sides of its valve plate 7c.The valve plate 7c has seal lands S1, S2 at opposite ends to close thereturn chambers 33, 34 formed at opposite ends between the land 21 andseal land 81 and between the land 22 and seal land 82. The valve block2c includes drilled holes providing return passages 83, 84 through thevalve block and which are adapted for connection to an inlet port ofpump 26. The valve plate 20, because of the seal lands employed, hasdrilled holes 85', 86 through the web portions adjacent the seal landsto interconnect return chambers on opposite sides of the valve plate.The valve block is made up of sections 91 through '95 in the mannerdescribed for the valve block 222 shown in FIG. 6. The valve head 3c ismade of a single block with transverse slots having spaced inserts 48therein as described and shown for the valve head 3 of FIG. 2.

FIGS. 10 and 11 show a four way fiat faced valve 161 having a pressuresupply passage 112 and pressure chamber 112a normally closed by centrallands 121 on opposite faces of a valve plate 103 and seal lands 122, 123that normally close return passages 115, 116 in the valve head 104 andvalve block 102. The valve plate 163 has transverse flow passages 125'provided by drilled holes through the lands and also through theintermediate portions of the valve plate. The valve head is providedwith a pressure chamber 112a in alignment with supply passage 112 and isalso provided with return chambers 117, 118 in alignment with returnpassages 115, 116 respectively, in the valve block.

The valve head 104 is made of a single block that is slotted across toestablish the return chambers 117, 118 and the pressure chamber 112a.The end portions of each of such slots are closed by spaced inserts 119suitably secured therein as are the inserts 48 in valve head 4.

The valve block 1G2 is made up of five sections 131 to 135 whoseadjoining vertical surfaces align with the critical metering edges ofthe lands and valve head. The central section 113 is made up of twoparts 133 and 133 spaced apart front to back to provide the pressuresupply passage 112. The central section 133 has a width equal to that ofthe central land 121 which normally blocks it. Abutting the centralsection are adjacent sections 132 and 134 each of which has a Widthequal to the spacing between the central land 12 and a seal land 122,123. Control passages 113, 114 are formed by vertically drilled holesthrough these adjacent sections. The vertical surfaces of the adjacentlands provide the metering edges for the valve block. The outer sectionseach have vertical slots abutting the adjacent sections and thesevertical slots provided the return passages 115, 116. The sections aerall secured by through bolts and are also welded along outer verticaljoints for securing their valve faces in coplanar relationship.

Various embodiments of the invention have been shown and described andit will be obvious that changes may be made therein within the spirit ofthe invention and the scope of the appended claims.

I claim:

1. A flat valve construction comprising a valve block having a firstfiat valve face, a valve head rigidly secured in spaced relation to saidvalve block and presenting a second fiat valve face, rectangularlyshaped control chambers formed in said first fiat valve face andcorresponding control chambers formed in said second flat valve face inalignment with said control chambers in said first fiat valve face, avalve plate having opposite symmetrically arranged third and fourth fiatvalve faces each formed by a pair of rectangular shaped lands alignedwith said control chambers when the valve is in a null position, a pairof leaf springs secured to opposite ends of said valve plate and toopposite sides of said valve block to support said valve plate betweensaid valve block and said valve head in closely spaced friction freerelation to said first and second fiat valve faces thereof and to permitrectilinear movement of said valve plate in op posite directions along aline through said lands for controlling fiuid flow through said valve,passage means through said valve plate interconnecting opposite faceportions thereof; said valve block comprising an assembly of parallelsections normal to said valve plate, bolt means parallel with said valvefaces securing said sections together so that their ends definingportions of said first valve face are coplanar, means integrally joiningadjacent said sections together along abutting side edges thereof; saidsections including a pair of end sections, a pair of control sectionseach adjacent one of said end sections, and a central section betweensaid control sec tions; said central section having a passage extendingtherethrough for supplying pressure fluid to pressure chambers formedbetween said lands in said valve plate and said central section alsohaving a width gauged to the spacing between said lands so that oppositeface of said central section provide sharply defined square edges in thefirst valve face; said control sections each comprising a pair of spacermembers spaced apart in the plane of its own section and having a widthequal to the width of one of said lands to space the end sections fromthe central section so that fiat vertical surfaces of said end sectionsand center section define walls of said control chamber and also providesharply defined edges in the first valve face which cooperate with theedges of the lands to de fine flow control orifices.

2. A flat valve construct-ion comprising a valve block having a firstfiat valve face, a valve head rigidly secured in spaced relation to saidvalve block and presenting a second fiat valve face, rectangularlyshaped control chambers formed in said first fiat valve face andcorresponding control chambers formed in said second fiat valve face inalignment with said control chambers in said first fiat valve face, avalve plate having opposite symmetrically arranged third and fourth flatvalve faces each formed by a pair of rectangular shaped lands alignedwith said control chambers when the valve is in a null position, a pairof leaf springs secured to opposite ends of said valve plate and toopposite sides of said valve block to support said valve plate betweensaid valve block and said valve head in closely spaced friction freerelation to said first and second flat valve faces thereof and to permitrectilinear movement of said valve plate in opposite direct-ions along aline through said lands for controlling fluid flow through said valve,passage means through said valve plate interconnecting opposite faceportions thereof; said valve block comprising an assembly of verticalsections normal to said valve plate, said sections including two endsections and a central section sandwiched between said end sections;said central section having a vertical hole extending therethroughdefining a passage for supplying pres sure fiuid to the pressurechambers formed between said lands in said valve plate, aligned verticalslots extending through opposite vertical faces of the central sectioneach having a depth gauged to the width of each of said lands, said endsections overlying said slots to define the control chambers in saidvalve block so that the vertical surfaces thereof and of the bottom ofthe slots provide sharply defined edges in the valve face of the valveblock which cooperate with the edges of the lands to provide four flowcontrol orifices of the valve, bolt means extending through saidsections parallel with said valve plate to secure said sections withtheir valve face portions coplanar, and Weld means integrally joiningsaid central section to said end sections along outer abutting edgesthereof for maintaining the valve face portions coplanar; said valveplate lands extending across said valve plate and having U-shapedinserts disposed between the lands on opposite sides of the valve plateso that the legs of the inserts provide end Walls for the pressurechambers formed thereby; and the valve head effecting a laminatedassem-' bly comprising a main valve head member having transverse slotsthere across gauged to the width of the lands for alignment therewithand having the portions of such slots extending beyond the lands closedby insert plates fitted and secured therein.

Dean Ian. 18, 1938 Shin-Ying Lee Mar. 3, 1959

1. A FLAT VALVE CONSTRUCTION COMPRISING A VALVE BLOCK HAVING A FIRSTFLAT VALVE FACE, A VALVE HEAD RIGIDLY SECURED IN SPACED RELATION TO SAIDVALVE BLOCK AND PRESENTING A SECOND FLAT VALVE FACE, RECTANGULARLYSHAPED CONTROL CHAMBERS FORMED IN SAID FIRST FLAT VALVE FACE ANDCORRESPONDING CONTROL CHAMBERS FORMED IN SAID SECOND FLAT VALVE FACE INALIGNMENT WITH SAID CONTROL CHAMBERS IN SAID FIRST FLAT VALVE FACE, AVALVE PLATE HAVING OPPOSITE SYMMETRICALLY ARRANGED THIRD AND FOURTH FLATVALVE FACES EACH FORMED BY A PAIR OF RECTANGULAR SHAPED LANDS ALIGNEDWITH SAID CONTROL CHAMBERS WHEN THE VALVE IS IN A NULL POSITION, A PAIROF LEAF SPRINGS SECURED TO OPPOSITE ENDS OF SAID VALVE PLATE AND TOOPPOSITE SIES OF SAID VALVE BLOCK TO SUPPORT SAID VALVE PLATE BETWEENSAID VALVE BLOCK AND SAID VALVE HEAD IN CLOSELY SPACED FRICTION FREERELATION TO SAID FIRST AND SECOND FLAT VALVE FACES THEREOF AND TO PERMITRECTILINEAR MOVEMENT OF SAID VALVE PLATE IN OPPOSITE DIRECTIONS ALONG ALINE THROUGH SAID LANDS FOR CONTROLLING FLUID FLOW THROUGH SAID VALVE,PASSAGE MEANS THROUGH SAID VALVE PLATE INTERCONNECTING OPPOSITE FACEPORTIONS THEREOF; SAID VALVE BLOCK COMPRISING AN ASSEMBLY OF PARALLELSECTIONS NORMAL TO SAID VALVE PLATE, BOLT MEANS PARALLEL WITH SAID VALVEFACES SECURING SAID SECTIONS TOGETHER SO THAT THEIR ENDS DEFININGPORTIONS OF SAID FIRST VALVE FACE ARE COPLANAR, MEANS INTEGRALLY JOININGADJACENT SAID SECTIONS TOGETHER ALONG ABUTTING SIDE EDGES THEREOF; SAIDSECTIONS INCLUDING A PAIR OF END SECTIONS, A PAIR OF CONTROL SECTIONSEACH ADJACENT ONE OF SAID END SECTIONS, AND A CENTRAL SECTION BETWEENSAID CONTROL SECTIONS; SAID CENTRAL SECTION HAVING A PASSAGE EXTENDINGTHERETHROUGH FOR SUPPLYING PRESSURE FLUID TO PRESSURE CHAMBERS FORMEDBETWEEN SAID LANDS IN SAID VALVE PLATE AND SAID CENTRAL SECTION ALSOHAVING A WIDTH GAUGED TO THE SPACING BETWEEN SAID LANDS SO THAT OPPOSITEFACE OF SAID CENTRAL SECTION PROVIDE SHARPLY DEFINED SQUARE EDGES IN THEFIRST VALVE FACE; SAID CONTROL SECTIONS EACH COMPRISING A PAIR OF SPACERMEMBERS SPACED APART IN THE PLANE OF ITS OWN SECTION AND HAVING A WIDTHEQUAL TO THE WIDTH OF ONE OF SAID LANDS TO SPACE THE END SECTIONS FROMTHE CENTRAL SECTION SO THAT FLAT VERTICAL SURFACES OF SAID END SECTIONSAND CENTER SECTION DEFINE WALLS OF SAID CONTROL CHAMBER AND ALSO PROVIDESHARPLY DEFINED EDGES IN THE FIRST VALVE FACE WHICH COOPERATE WITH THEEDGES OF THE LANDS TO DEFINE FLOW CONTROL ORIFICES.